U.S. patent number 7,357,372 [Application Number 10/536,740] was granted by the patent office on 2008-04-15 for seat ring for butterfly valve.
This patent grant is currently assigned to Asahi Organic Chemicals Industry Co., Ltd.. Invention is credited to Akihiro Shakagori, Yukitomo Yamamoto.
United States Patent |
7,357,372 |
Shakagori , et al. |
April 15, 2008 |
Seat ring for butterfly valve
Abstract
A seat ring having a hollow cylindrical body portion with a
flange surface as each of its side surfaces. The cylindrical body
portion has stem through-holes above and below along a stem axial
direction X and a stem penetrates said through-holes. An outer
circumference of the body portion is formed in an elliptic shape
with the stem axial direction X as its longitudial axis. The
thickness of the body portion where the stem through-holes are
provided is the maximum while the thickness of the body portion
along an axis perpendicular to the longitudinal axis is the
minimum.
Inventors: |
Shakagori; Akihiro (Nobeoka,
JP), Yamamoto; Yukitomo (Kitakyushu, JP) |
Assignee: |
Asahi Organic Chemicals Industry
Co., Ltd. (Miyazaki-ken, JP)
|
Family
ID: |
32463019 |
Appl.
No.: |
10/536,740 |
Filed: |
January 12, 2003 |
PCT
Filed: |
January 12, 2003 |
PCT No.: |
PCT/JP03/15319 |
371(c)(1),(2),(4) Date: |
November 07, 2005 |
PCT
Pub. No.: |
WO2004/051122 |
PCT
Pub. Date: |
June 17, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20060163520 A1 |
Jul 27, 2006 |
|
Foreign Application Priority Data
|
|
|
|
|
Nov 29, 2002 [JP] |
|
|
2002-349188 |
|
Current U.S.
Class: |
251/306;
123/337 |
Current CPC
Class: |
F16K
1/2265 (20130101) |
Current International
Class: |
F16K
1/22 (20060101) |
Field of
Search: |
;251/305,306,307,308
;123/336,337 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
3-29776 |
|
Mar 1991 |
|
JP |
|
3-29777 |
|
Mar 1991 |
|
JP |
|
3-62271 |
|
Jun 1991 |
|
JP |
|
6-17946 |
|
Jan 1994 |
|
JP |
|
7-12766 |
|
Mar 1995 |
|
JP |
|
2001-124218 |
|
May 2001 |
|
JP |
|
2001-214980 |
|
Aug 2001 |
|
JP |
|
Primary Examiner: Fristoe, Jr.; John K.
Attorney, Agent or Firm: Jordan and Hamburg LLP
Claims
The invention claimed is:
1. A seat ring assembly for a butterfly valve comprising: a tubular
body portion defining a valve body axis along a tubular direction
of the tubular body portion, the tubular body portion having two
side flange surfaces disposed at opposing body portion ends, said
tubular body portion having at least one stem through hole
extending in a radial direction of said tubular body portion and
defining a stem axis; an outer circumference portion of said
tubular body portion being formed having an elliptic shape taken in
a plane perpendicular to said valve body axis with a stem axial
direction as a longitudial axis of said elliptic shape; an inner
circumference portion of said body portion formed having a circular
shape taken in the plane perpendicular to said valve body axis and
a constant radius; an annular protrusion protruding radially
outwardly from an axial center of said outer circumference portion
of said body portion; a valve plug body defining a circular through
valve body opening, said tubular body portion being installed in
said circular through valve body opening in a compressed state such
that said outer circumference portion is compressed at areas
intersected by said longitudinal axis of said elliptic shape such
that said inner circumference portion is deformed from said
circular shape to an elliptic shape; and wherein a ratio of a first
thickness dimension of the body portion from the inner
circumference portion to the outer circumference portion in the
stem axial direction to the thickness dimension in the direction
perpendicular to the stem axis from the inner circumference portion
to the outer circumference portion is 1.01:1 to 2:1.
2. The seat ring assembly for a butterfly valve according to claim
1, said annular protrusion having a rectangular sectional
shape.
3. The seat ring assembly for a butterfly valve according to claim
1, wherein said at least one stem through hole includes two stem
through-holes, each of said stem through holes having on a
periphery portion a boss portion.
4. The seat ring assembly for a butterfly valve according to claim
1, further comprising a lug portion on an upper end of each flange
surface.
5. The seat ring assembly for a butterfly valve according to claim
1, wherein said tubular body is made of at least one of EPDM, NBR
or PVDF.
6. The seat ring assembly for a butterfly valve according to claim
1, wherein said at least one stem through hole includes two stem
through-holes, each of said stem through-holes having a ring.
Description
TECHNICAL FIELD
This invention is in regards to a seat ring for butterfly valves
suitable for use in piping lines at chemical plants, in water
supply and sewerage systems, for agriculture and fishery, and so
on. More details are as follows. The performance improvement of the
seat ring seal near the stem through-hole without the increase in
the stem's torque operation, and the performance improvement of
countering fluid leaching through the gap between the stem
through-hole on the inner circumference of the seat ring and the
stem.
BACKGROUND ART
The butterfly valve known up until now is the one that by attaching
an elastic seat ring to the inside of the hollow cylindrical body
made of rigid material and inserting the valve plug, opens and
closes by the seat ring crimping and separating due to the rotating
stem. For the butterfly valve, what is used is a seat ring having a
circular outer circumferential shape and an inner circumferential
diameter formed smaller than the outer circumferential diameter of
the valve plug by one size. However, there was a drawback to this
butterfly valve. When the valve plug is crimped and sealed to the
inner circumferential part, since the available surface pressure is
low near the stem through-hole, the sealing effect is small with
the same compression rate, making it vulnerable to leakage.
In order to solve the above problem, the seat ring as described in
the Japanese Unexamined Utility Model Publication No. 3-62271 (FIG.
1, Pages 4 to 5) was developed. This is a seat ring for the
butterfly valve to improve the sealing performance near the stem
through-hole. As shown in FIGS. 5 to 7, it has a circumferential
shaped protrusion 24 represented by a trajectory with a radius
R.sub.1 and O.sub.1 as its center on its body circumference
attaching surface 23 which is smaller in width than the body
attaching surface 23. Furthermore, it is distinctive in that it has
a circular protrusion 25 which is smaller in width than the above
protrusion 24 and is decentered toward the stem axial direction X'
on the surface of protrusion 24, has a center at a point O.sub.2
decentered to the stem axial direction X' with respect to the
center O.sub.1, and is represented by a trajectory with a radius
R.sub.2 smaller than the above radius R.sub.1. Due to this
technology, a crushing margin near the stem through-holes 26 and 27
is made larger when the valve is blocked, allowing for the
improvement of sealing performance.
However, with this type, as shown in a circular mark portion in
FIG. 6 and in FIG. 7, with an outer circumferential shape of a seat
ring 21, two circular outer circumferences with different diameters
and center positions are brought into contact with the seat ring 21
and the body attaching portion, and a crossing portion 28 of the
two outer circumferences is inflected, and not smooth. Therefore,
the sealing pressure at the outer circumferential crossing portion
28 is smaller in the fully closed state, which leads to the
possibility of leakage from the portion on the flow passage side.
Moreover, at the pressure contact portion between the valve plug 22
and the seat ring 21 near the stem through-holes 26 and 27, with
double protrusions of 24 of 25 and thickness changing as shown in
FIG. 8, the available surface pressure (shown by an arrow) is not
even. That constituted a problem of fluid leaching through the gap
between the stem through-holes 26 and 27 of the seat ring 21 and
the stem.
DESCRIPTION OF THE INVENTION
This invention was made in view of the above problems of the prior
art, and its objective was to provide a seat ring for the butterfly
valve whose valve-seat sealing performance near the stem
through-hole and the sealing performance countering leaching of
fluid through the gap between the stem through-hole on the inner
circumference of the seat ring and the stem (hereinafter referred
to as the "internal leakage from the stem through-hole") are
improved without the increase of the stem's torque operation.
In order to achieve the above objective, with this invention, as
shown in FIGS. 1 and 2, for the butterfly valve seat ring having a
flange surface 6 on both its side surfaces of the hollow
cylindrical body portion 5, an outer circumference 7 of the body
portion 5 is formed in an elliptic shape with the stem axial
direction X as its long axis, and an inner circumference 8 in a
circular shape.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal sectional view of the seat ring for the
butterfly valve illustrating an embodiment of this invention.
FIG. 2 is a partially broken perspective view of this embodiment's
seat ring for the butterfly valve.
FIG. 3 is a front view showing the butterfly valve in the opened
state, with this embodiment's seat ring attached.
FIG. 4 is a conceptual diagram of the available surface pressure
between the valve plug and the seat ring in FIG. 3.
FIG. 5 is a plan view of a conventional seat ring.
FIG. 6 is a longitudinal sectional view of the conventional seat
ring.
FIG. 7 is an enlarged view of FIG. 6's essential part.
FIG. 8 is a conceptual diagram of the available surface pressure
between the valve plug and the seat ring in a conventional
butterfly valve.
BEST CONFIGURATION FOR CARRYING OUT INVENTION
In FIGS. 1 and 2, 1 is a seat ring made of EPDM, in which a hollow
cylindrical body portions 5 and a flange surface 6 on both its side
surfaces are formed integrally. Above and below the stem axial
direction X on the body portion 5, there are stem through-holes 9
and 10 through which a stem 3, which will be described in detail
later, penetrates. An outer circumference 7 of the body portion 5
is formed in an elliptic shape with the stem axial direction X as
its long axis. More specifically, this is there so that the
thickness of the portion on which the stem that has through-holes 9
and 10 becomes the maximum while the thickness b of the horizontal
portion when both of them are moved by 90 degrees becomes the
minimum. It is preferable that the ratio of the thickness dimension
of the stem axial direction X from the inner circumference 8 to the
thickness dimension b of the direction Y perpendicular to the stem
axis from the inner circumference 8 is formed at 1.01:1 to 2:1. If
it is larger than 1.01:1, the stem's torque operation will not
increase and valve-seat leakage near the stem through-holes 9 and
10 will unlikely occur. Also, if it is smaller than 2:1, there is
no problem with assembling performance and leakage from the valve
seat near the direction Y perpendicular to the stem axis and
internal leakage from the stem through-holes 9 and 10 will unlikely
occur. Moreover, it is more preferable that the ratio is formed at
1.03:1 through 1.43:1.
The center of the outer circumference 7 has an annular protrusion
11 with a rectangular sectional shape, and is fitted into a groove
on the inner circumferential surface of valve plug 2, which will be
described in detail later, so that the seat ring 1 does not move. A
ring 12 made of SUS is attached on the periphery of the stem
through-holes 9 and 10 of the outer circumference 7. Also, the
inner circumference 8 from which a valve plug 4, which will be
described in detail later, is crimped and separated is formed as a
flat surface in a circular shape, and the spherical shape boss
portions 13 and 14 with a shape corresponding to the valve plug 4
are provided on the periphery portion of the stem through-holes 9
and 10, so that the valve-seat sealing performance improves. An
outer circumference 15 of a flange surface 6 put integrally on both
sides of the above body portion 5 is formed in a circular shape,
and a lug portion 16 provided on the upper end of the flange
surface 6 with protruding inwards is fitted to the outer
circumferential surface of the valve plug 2, and prevents the seat
ring 1 from moving. Since the inner circumference of the opening 17
provided at the center of the valve plug 2 is a circular shape
while the outer circumference 7 of the seat ring 1 is an elliptic
shape, when the seat ring 1 is fitted into the valve plug 2, a flow
passage 18 formed on the inner circumference 8 of the seat ring 1
is an elliptic shape with the stem axial direction X as its short
axis.
In this embodiment, the material of the seat ring 1 is EPDM, but it
is not necessarily limited to this, and rubber such as NBR or a
synthetic resin such as PVDF may be used as long as there is no
problem with strength or corrosion resistance. Also, in this
embodiment, the annular protrusion 11 is put on the outer
circumference 7 of the seat ring 1, a ring 12 around the stem
through-holes 9 and 10, and a lug portion 16 on the flange surface
6, respectively, but they need not be provided especially if there
is no problem with performance.
Each embodiment of this invention will be described below based on
drawings, but needless to say, this invention is not limited to
these embodiments.
FIG. 3 is a front view showing the butterfly valve in the opened
state, with this embodiment's seat ring attached. In FIG. 3, 2 is a
valve plug made of PP which has an almost disk shaped top flange 19
protruding toward the outer circumference on its top. A circular
shaped opening 17 is provided at the center of the valve plug 2,
and on the inner circumferential surface of the opening 17, a seat
ring 1 is made attachable. A recess portion is provided at the
center of the inner circumferential surface of the opening 17, and
has a recess portion so that the protrusion 11 at the center of the
outer circumference of the seat ring 1 can be fitted to it. If
there is no protrusion 11 at the center of the outer circumference
7 of the seat ring 1, it is not unnecessary to provide a recess
portion at the center of the inner circumferential surface of the
opening 17.
The stem 3 shown in FIG. 3 is a stem made of SIS403, and the upper
end of the stem 3 is arranged so that it is protruding from the
center of the top flange 19 provided on the top of the valve plug
2. Also, the center of the stem 3 is closely penetrated by the
valve plug 2 and the seat ring 1 in a rotatable state.
The valve plug 4 shown in FIG. 3 is a valve plug in a circular
shape made of PP arranged at the center inside the valve plug 2 and
supported by the stem 3 penetrating the center of the valve plug 4
disabling rotating. The valve plug 4 rotates within the valve plug
2 along with the rotating of the stem 3, and when the outer
circumferential edge 20 of the valve plug 4 is crimped and
separated from the inner circumference 8 of the seat ring 1, the
valve opens and closes.
Next, the actuation of the butterfly valve to which this
embodiment's seat ring is attached, is described.
When the stem 3 is rotated from the valve's fully opened state in
FIG. 3 the valve plug 4 rotates along with it, and the outer
circumferential edge 20 of the valve plug 4 is crimped into the
inner circumference of the seat ring 1 and fully closes. At this
time, the outer circumferential edge 20 of the valve plug 4 seals
the inner circumference 8 of the seat ring 1 as if crushing it.
However, since the outer circumference 7 of the seat ring 1 is
formed in an elliptic shape with the stem axial direction X as its
long axis, the crushing margin of the inner circumference 8 of the
seat ring 1 by the outer circumferential edge 20 of the valve plug
4 becomes larger by a portion raised near the stem through-holes 9
and 10. Therefore, the valve-seat sealing performance near the stem
through-holes 9 and 10 are improved. Moreover, as shown in FIG. 4,
since the annular protrusion 11 at the center of the outer
circumference 7 is formed in a rectangular sectional shape, the
thickness is even and the available surface pressure also becomes
even (shown by an arrow), whereby internal leakage through the stem
through-holes 9 and 10 will unlikely occur. Also, since the
crushing margin of the inner circumference 8 of the seat ring 1 in
the direction Y perpendicular to the stem axis by the outer
circumferential edge 20 of the valve plug 4 is provided at the
required minimum to secure the valve-seat sealing performance, the
stem's torque operation stays small, and the valve-seat leakage in
the direction Y perpendicular to the stem axis does not occur.
As this invention is constituted as above, the following effects
can be obtained.
Since the outer circumference of the seat ring is formed in an
elliptic shape with the stem axial direction as its long axis, the
valve-seat sealing performance near the stem through-holes and the
sealing performance countering the leaching of fluid through the
gap between the stem through-hole of the seat ring inner
circumference and the stem can be improved without the increase of
the butterfly valve's stem's torque by 30 to 50% as compared with
conventional cases.
INDUSTRIAL APPLICABILITY
As described above, this invention, the seat ring for the butterfly
valve, can be used for piping lines at chemical plants, in water
supply and sewerage systems, for agriculture and fishery, and so
on, with its seat ring's improved valve-seat sealing performance
near the stem through-hole and a sealing performance to counter
fluid from leaching through a gap between the stem through-hole in
the seat ring inner circumference and the stem without the increase
in the stem's torque operation.
* * * * *